The metric measures everyone aged 16 and older who is not in the labor force, the vast majority of which are not in the labor force for very good reasons.
For one example, young people in high school, college and graduate school are included in this number. In 2017 they number about 37 million people.
For another, in March 2017 another 45.7 million were over 65 and getting Social Security. In other words, retired.
Together that's nearly 88% of the current 94.4 million "not working".
That leaves 11.7 million "not working", some of whom are disabled receiving Social Security but some disabled are still working, trying to lead productive lives despite their handicaps.
Typically the rest are homemakers, who are trying to make sure their kids aren't rotten like yours.
George Mason University should take away Steve Moore's MA in economics, if you ask me.
And even if you don't.